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Why don't guitar amps use Toroidal Transformers

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4/28/2003 1:05 AM

Why don't guitar amps use Toroidal Transformers

Hi there,

I am new here with a million questions on starting out. I have seen toroidal transformers used in Aguilar Tube Bass amps and wondered why more companies don't use them?
Apart from the question above is there a book that will teach me how to build a guitar tube amp using off the shelf parts and explain what each part does.
I have seen many books around but they don't seem to tell me why I am doing something. ie why do I need to put a capacitor here, or why do I need to put in a choke or what to I do if my country's power is 240 volts.

Can anyone help? I would like to get started learning.

By the way, this is a great site!

Regards

Ronald Harting

4/28/2003 1:49 AM
Bob Predaina	i think that Mesa uses toroids in their rackmount amps.

4/28/2003 2:02 AM
Ronald	Hey Bob, I is there a tone difference between the both of them? Ronald

4/29/2003 4:06 PM
OTP	Bruce Egnator used toriods, in his amps.

4/28/2003 12:46 PM

Hi, Ronald. Toroidal power trannys are more expensive to make, which is the most likely reason they aren't used very much. They tend to be lighter and quieter though.

The output trannys are supposed to be great, except for two reasons: 1) toroids poorly handle mismatched currents (badly matched tubes) in a push-pull stage, and 2) a significant part of the tone of an output tranny is in the lamination material; toroids use ferrite which is way different. The toroidal OT's are probably better choices in hifi applications.

4/28/2003 7:54 PM

Like MKB posted they don't like mismatched currents.

FWIW I have a laney vc 30 with a toroidal PS transformer. I installed Polypro PS caps and had loud power transformer mechanical noises. Polypros have very low ESR. A .82 ohm resistor after the PS SS diodes and before the first PS cap took care of the noises.

The small current conduction difference in the two SS diodes caused the problem. What would happen in an output stage??????

5/2/2003 10:56 AM
oskar	The toroidal power tranformers have more bandwidth that the EI ones , in order to reduce the noise present at mains line , it would be necesarry to install a line filter.

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